package com.codewater.springcloud.lb;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * @author ： CodeWater
 * @create ：2022-07-16-16:41
 * @Function Description ：手写负载均衡（这里是用自己写的）
 */
@Component
public class MyLB implements LoadBalancer{
    private AtomicInteger atomicInteger = new AtomicInteger(0);
    
    public final int getAndIncrement(){
        int current ;
        int next;
        
        do{
            current = this.atomicInteger.get();
            next = current >= 2147483647 ? 0 : current + 1;
        }while( !this.atomicInteger.compareAndSet(current , next) );
        System.out.println( "***********第几次访问， 次数next： " + next );
        return next;
    }

    //负载均衡算法：rest接口第几次请求数 % 服务器集群总数量 = 实际调用服务器位置下标  ，每次服务重启动后rest接口计数从1开始。
    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances ){
        int index = getAndIncrement() % serviceInstances.size();
        return serviceInstances.get(index);
    }
}
